I made a doodle survey to find the best appointment for a tournament. Don't consider the date, only the weekday is important and the time-zone depends on the ip-address: http://doodle.com/udrr2dvp6zgches9

Anytime works for me as long as you can broadcast the times to owners of the game somehow. I don't use FaceBook or Twitter so having an in-game newsfeed of some type of Steam related anouncement would help.